Preparation, Formation Mechanism And Preventive Effect On Type â…¡ Diabetes Mellitus Of A Novel Functional Rice With High Rs4 Content

The functional rice has attractive prospect because of unique advantages of staple food which can interfere with the lack of nutrition or metabolic diseases easily.Resistant starch has been accepted as a new type of high-quality dietary fiber because of the positive effect in the prevention of cardiovascular disease,diabetes mellitus,and gastrointestinal cancer.The bad eating quality results in overmuch of early indica rice in China.Preparation of high resistant starch(RS) staple food with early indica rice can improve the eating quality and functional properties,which has significance in not only current global foodstuff crisis,but also global public health problem due to "high-fat & low-fibre" diet.In this research,the rice with high RS4 content was prepared with low-value early indica rice by acetylation of starch in whole rice through freezing method to enhance mass transfer.Subsequently,the eating quality was assessed.The formation mechanism of RS4 was investigated with instrument analysis.Preliminary security evaluation was carried out by toxicological method.Based on this,preventive effects of functional rice with high RS4 content on typeâ…¡diabetic mellitus was evaluated systemically.Main research results:1.The optimal technology parameters and conditions which produced the rice with highest RS4 content(73.19%) were as follows:the ratio of rice and Na₂CO₃ aqueous solution was 1g:3mL,freezing time was 6h,reaction temperature was 30℃,pH 10,the ratio of solvent and solid was 2.0mL:10g,and reaction time was 5h.The RS4 content of samples of the mono-factor experiments was all beyond 53%while the content of acetyl group was range from 0.59%to 5.30%.There was no significant correlation between RS4 and acetyl group content by statistical analysis which provided a green,mild,and economical technology in industry.The slow digestible starch(SDS) content of modified rice increased slightly,and the RS content increased obviously after dry-heat treatment.2.FT-IR,SEM,XRD,and DSC were employed to investigate the formation mechanism of RS4.The results showed that starch molecule in whole rice suffered substitution with low degree because of the enhancement of acetylation due to the effect of freezing penetrate and the destruction of partial crystal region by ice crystal.And it appeared not only in the amorphous region but also the crystal region.The main part inside the starch granule which wasn't substituted in amorphous region because of mass transfer resistance was hydrolyzed byα-amylase,and formed hollow structure.Crystal form of acetylated starch with low degree of substitution(DS) changed slightly.Part of crystallite structure(2θ18°) was destroyed a little only when the acetyl group content beyond 3.25%,and then the cry stallinity,heat of crystalloid fusion,gelatinization temperature,and gelatinization enthalpy all decreased.SEM,XRD,and DSC indicated that the resistance to enzymatic degradation of acetylated starch with low DS was obtained from the obturation of functional group on crystal district of starch granules.3.The results of the rice with high RS4 content of gel consistency,alkali spending, RVA,and TPA showed that,compared with the original rice,the eating quality improved, and setback value reduced by about 3/4 which implied the ability of anti-staling improved after cooking.Determination of amylose content was no longer suitable to evaluate the eating quality as the key index because of the destruction of starch structure.Also, cooking properties couldn't estimate the cooking quality effectively due to the integrality change of rice granule.Therefor,a new method should be established for the modified rice.4.Acute toxicity test demonstrated the rice with high RS4 content was non-toxic.30 days feeding test explained the rice with high RS4 content was no harmful to growth, hematopoietic function and liver or kidney function of rats.Estimated maximum non-effect dose was more than 50g/kg,so it was safety for human being.The rice with high RS4 content might have amino acid-sparing effect,which increased the weight of rats.The level of total cholesterol,triglyceride and blood urea nitrogen was decreased in 30 days feeding test.It is suggested that the rice with high RS4 content could protect kidney and improve lipid metabolism.5.The intervention of feedstuff added the rice with high RS4 content on typeâ…¡diabetes mellitus rats showed RS4 could reduce postprandial plasma glucose,hepatic glycogen and hepatic glucose output,increase insulin sensitivity,improve the disorder of glucolipid metabolism of typeâ…¡diabetes mellitus.Pathological examination suggested that RS4 showed positive prevention from fatty liver which induced by high-sucrose and high-fat feedstuff.